As Daisy said, dieting isn't a canned formula. That's what is so scary about these fad diets. For example, the Atkins Diet - yea, its low carb. But it skips the part about eating good quality fats, not just any fat you want but totally cutting your carbs. It may "work" in the short term, but it is not a healthy lifestyle in the long run. On the other side, if you focus on a 'low fat' diet like used to be so popular, well then you screw yourself out of another important part of a healthy diet. It isn't one or the other.
The point is to find a healthy balance of all these things: fats, carbs & proteins as well as enzymes and other nutrients that are found in foods and can't be thrown in as a supplement. At the end of the day, I think the most important thing to keep in mind for a healthy diet is "moderation in everything" and also variety. A restricted diet may help you to drop some fat initially, but again, you need to give your body what it needs. This goes to an earlier question you had about how long does one diet. Generally a particular approach will run 8-16 weeks - it takes at least 3 weeks to see any sort of result from any particular type of eating, and then it still takes time for your body to adjust to a particular type of eating and then to hit its stride to get some reasonable results that will hold. For example, you might follow a particular diet that is rather restricted in what you can eat (e.g. chicken, steak, oatmeal, green vegetables, flax oil) - run it for say 12 weeks, get your results, but then ease up on the restrictions - throw in an apple or some other fruit for variety - fruits provide enzymes that your body needs to help clean out the byproducts of a restricted diet.